Mass-number and isotope dependence of the local microscopic optical potential for polarized proton scattering

Abstract

We derive local microscopic optical potentials $U$ systematically for polarized proton scattering at 65~MeV using the local-potential version of the Melbourne $g$-matrix folding model. As target nuclei, we take $^{6}$He and neutron-rich Ne isotopes in addition to stable nuclei of mass number $A=4$--$208$ in order to clarify mass-number and isotope dependence of $U$. The local potentials reproduce the experimental data systematically and have geometries similar to the phenomenological optical potentials for stable targets. The target density is broadened by the weak-binding nature and/or deformation of unstable nuclei. For the real spin-orbit part of $U$ the density broadening weakens the strength and enlarges the radius, whereas for the central part it enlarges both of the strength and the radius. The density-broadening effect is conspicuous for halo nuclei such as $^{6}$He and $^{31}$Ne. Similar discussions are made briefly for proton scattering at 200~MeV. We briefly investigate how the isovector and the non spherical components of $U$ affect proton scattering.